1. Field of the Invention
This invention is related to a semiconductor device and its manufacturing method, a circuit board and an electronic device.
2. Description of the Related Art
Various types of package technologies are known for semiconductor integrated circuits, i.e. ICs. A popular type of these IC package technologies is plastic-sealed packaging. In a typical plastic-sealed package, or xe2x80x9cplastic packagexe2x80x9d, a semiconductor die composing an integrated circuit is typically attached to an interposer substrate by means of a die attach adhesive agent. In addition to providing support for the IC die, the interposer substrate typically provides a lead frame with a conductive path to externally accessible pins, bumps or other type of internal-to-external electrical interface. After the circuit on the IC die is electrically connected to the lead frame, a plastic sealant is used to encase the IC die, die attach adhesive, lead frame, and substrate interposer to form a plastic package.
In circuit board assembly processes, it is typically to first place multiple ICs on a printed circuit board, PCB, without soldering. Once the ICs are in place, the PCB undergoes a process known as solder reflow, or xe2x80x9creflowxe2x80x9d, in which the PCB is passed over a solder bath and the multiple ICs are thereby soldered in place. A difficulty associated with the use plastic package IC devices in reflow or other high temperature processes, however, is that the adhesive agents used to attach an IC die to an interposer substrate typically have moisture and air bubbles that may expand to become vapors under these high temperature processes. The expanding vapors may introduce cracks into the plastic package, introduce moisture into the IC die, or otherwise damage or weaken the IC device.
An object of the invention is to overcome such conventional problems.
Another object of the present invention is to provide an IC package, and method for IC packaging, in which a vapor or other gas may be removed from a sealed package without damaging the package.
(1) A. semiconductor device in accord with the present invention includes a substrate having a raised portion on one surface where at least a wiring pattern is partially formed, a sheet supported on the raised portion such that the sheet is maintained apart from the surface of said substrate, a semiconductor die is attached with an adhesive agent onto the sheet, and a sealed portion that seals the semiconductor die on the sheet, wherein the sheet has gas permeable region at least in a region where said adhesive agent isplaced.
According to the present invention, a space is formed between the sheet and the substrate so that gas generated in the adhesive agent can be released through a the gas permeable region of the sheet.
(2) In this semiconductor device, the sheet may have a penetrating, i.e. perforating, hole at least in the region where said adhesive agent is placed.
(3) In this semiconductor device, the raised portion may have a wiring pattern and a resist layer may cover over the wiring pattern.
(4) In this semiconductor device, the raised portion may be formed in a region including an end portion of the substrate.
(5) In this semiconductor device, the semiconductor die may be electrically connected to the wiring pattern by means of wire bonding.
(6) In this semiconductor device, the sheet may be have opening over the regions designated for wire bonding onto the wiring pattern.
(7). In a circuit board in accord with the present invention, a semiconductor device as described above may be installed.
(8) In an electronic device in accord with the present invention, a semiconductor device as described above may be installed.
(9) A method of manufacturing a semiconductor device in accord with the present invention includes the steps of: sealing a semiconductor die with plastic, using an adhesive agent to adhere the semiconductor die to a sheet, supporting the sheet with an upper end of a raised portion formed on a substrate so as to maintain the sheet apart from the surface of the substrate, assuring the sheet has a be gas permeable region in a region where said adhesive agent is placed, making the raised portion have a wiring pattern and sealing the semiconductor die onto the sheet.
According to the present invention, a space is formed between the sheet and the substrate so that gas generated in the adhesive agent can be released through the permeable region.
(10) A method of manufacturing the present semiconductor device may further include a step of connecting the semiconductor die to the wiring pattern using wire bonding before sealing the semiconductor onto the sheet.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.